sched/core: Clear prev->dl_server in CFS pick fast path

commit a741b82423f41501e301eb6f9820b45ca202e877 upstream.

In case the previous pick was a DL server pick, ->dl_server might be
set. Clear it in the fast path as well.

Fixes: 63ba8422f876 ("sched/deadline: Introduce deadline servers")
Signed-off-by: Youssef Esmat <youssefesmat@google.com>
Signed-off-by: Daniel Bristot de Oliveira <bristot@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Juri Lelli <juri.lelli@redhat.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/7f7381ccba09efcb4a1c1ff808ed58385eccc222.1716811044.git.bristot@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 875fc6e720757f2d329fc81f9e3fc1f2c3ecff79..0cfb5f5ee2133994cbce832c7231272e6dd3931a 100644 (file)
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -6043,6 +6043,13 @@ __pick_next_task(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)
                        p = pick_next_task_idle(rq);
                }
 
+               /*
+                * This is a normal CFS pick, but the previous could be a DL pick.
+                * Clear it as previous is no longer picked.
+                */
+               if (prev->dl_server)
+                       prev->dl_server = NULL;
+
                /*
                 * This is the fast path; it cannot be a DL server pick;
                 * therefore even if @p == @prev, ->dl_server must be NULL.